iOS: December 2016

Activities
They dictate the UI and handle the user interaction to the smart phone screen.

public class MainActivity extends Activity {
}

Services
They handle background processing associated with an application.

public class MyService extends Service {
}

Broadcast Receivers
They handle communication between Android OS and applications.

public class MyReceiver  extends  BroadcastReceiver {
   public void onReceive(context,intent){}
}

Content Providers
They handle data and database management issues.

public class MyContentProvider extends  ContentProvider {
   public void onCreate(){}
}

	Fragments Represents a portion of user interface in an Activity.
	Views UI elements that are drawn on-screen including buttons, lists forms etc.
	Layouts View hierarchies that control screen format and appearance of the views.
	Intents Messages wiring components together.
	Resources External elements, such as strings, constants and drawable pictures.
	Manifest Configuration file for the application.

iOS